The style of pizza eaten today in the United States originated in Naples, Italy. The poorer citizens of Naples primarily lived outdoors, so they needed fast meals that could be eaten outdoors. Flat breads with toppings fulfilled the need, which developed in the 18th and 19th century.
One pizza in particular, the pizza mozzarella, became popular when Queen Margherita demanded to try several varieties after growing weary of what she was used to eating. The pizza she liked best with cheese, tomatoes and basil was eventually christened pizza Margherita after her. Pizza migrated to the U.S. when immigrants from Naples brought the traditional crusts, cheeses and toppings with them and started serving them in restaurants.